ByMatthew ShaerOctober 28, 2011

Android remains the most popular mobile OS in the US. And according to one new report, Android had also become the leader in app downloads – an arena once dominated by Apple and its online App Store. In the second quarter of 2011, the analytics firm ABI announced this week, Android was responsible for 44 percent of all mobile app downloads, compared to 31 percent on Apple's iOS.

"Android’s open source strategy is the main factor for its success," Lim Shiyang, research associate at ABI, said in a statement. "Being a free platform has expanded the Android device install base, which in turn has driven growth in the number of third party multi-platform and mobile operator app stores. These conditions alone explain why Android is the new leader in the mobile application market."

Of course, Apple still rules in one very important metric: per-user downloads. "Despite leading in total mobile application downloads, Android’s app downloads per user still lag behind Apple’s by 2-to-1," reads the ABI press release. "Apple’s superior monetization policies attracted good developers within its ranks, thus creating a better catalog of apps and customer experience."

As of August, the Android OS had opened up a safe lead over Apple. ComScore estimated in August that Android made up 43.7 percent of the market, up 5.6 percentage points from the prior three-month period. Apple, meanwhile, had shored up its spot in the number 2 slot, growing 0.7 percentage points to 27.3 percent. RIM, meanwhile, slipped 5 points from May, to settle at 19.7 percent.